With a smaller workforce, the increased number of employees calling out sick has put the brunt of the shutdown on smaller airports, TSA spokesperson Jim Gregory acknowledged to ABC News. When employees are calling out across the board, the small teams at airports like Palm Springs feel it first.

But Gregory stressed the country's airports and airlines would not be imperiled by any hit to security operations, citing strict standards and a program that sends screeners and managers from airports under less stressful circumstances to any airport needing backup. Dubbed the "National Deployment Force," TSA has the ability to quickly dispatch more frontline screeners, canine teams and specially trained Homeland Security personnel. They are often used during major events like the Super Bowl or in the wake of natural disasters when hometown TSA employees are unable make it to work.

The email was written Monday by Martin Elam, a deputy federal security director, to all TSA staff at the Palm Springs airport and mentioned "excessive unscheduled absences recently experienced at PSP," and threatened disciplinary action.

"Your unauthorized unscheduled absence will be coded by payroll as absent without leave (AWOL)," Elam wrote. "At the conclusion of the government shutdown, an employee's AWOL status may result in progressive disciplinary action."

TSA spokesperson Michael Bilello on Monday said that 4.6 percent of TSA employees did not show up for work on Monday nationwide, compared to 3.8 percent on the same day in 2018.

Many Democrats spent the day decrying the shutdown and its effect on thousands of federal employees tasked with protecting America's skies and airports.

"There will come a breaking point for many of these individuals and families. Why are we doing this? Why are we pushing them to the point where they've got their minds on their children, and who's going to take care of them, and who's going to pay for day care?” Sen. Dick Durbin, D-Illinois told reporters at Chicago O'Hare International Airport.